Showing papers on "Benthic zone published in 1972"

Stability and Trophic Structure in Deposit-Feeding and Suspension-Feeding Communities

Abstract: Suspension-feeding benthic marine organisms feed by straining particles from the overlying water. Deposit feeders feed by ingesting bottom sediments. These two alternative strategies bring about many differences in food predictability, interspecies interactions, and population dynamics. Because suspension feeders rely principally upon phytoplankton for food, they are subject to a very unpredictable energy source. This results in few permanent sets of species associations due to competitive interactions, great fluctuations in population size, and patchy distributions. Deposit feeders that rely upon great amounts of water-borne detritus are subject to the same lack of predictability. However, where the rate of sedimentation of organic detritus is not so high, the food source for deposit feeders is much more predictable. This is because bacteria provide the rate-controlling step for the generation of food, and organic matter resides in the bottom as a "sink," buffering benthic deposit-feeders against fluctua...

Cretaceous bathymetric distribution of benthic foraminifers

Abstract: Model based on comparison with Recent forms, numerical analysis of depth of restricted genera, overlapping ranges of indicative species, faunal diversity and abundance, California

Effect of river outflow management on marine life

Abstract: Construction of the Aswan High Dam in Egypt, and subsequent cessation (since 1965) of surplus Nile Flood water (ca 35 billion m3 of water annually) from discharging into the Mediterranean Sea, has had an impact on marine life in coastal waters adjoining the Nile Delta and on brackish-water life in the lakes Nutrient concentrations have fallen considerably in these waters; phytoplankton blooms associated with the Nile Flood have disappeared and, consequently, Sardinella catches have dropped from ca 15,000 tons in 1964 to 4,600 tons in 1965 and to 554 tons in 1966 Depletion of nutrients, reduction of organic matter and of mud and silt deposition, affect also benthic life on the Continental Shelf and in brackish-water lakes adjoining the sea Lake fisheries have also suffered from reduction in potential area and abstruction of free connection with the sea, thus hindering spawning migrations of mugils, shirimp and eel Marine erosion of the Delta Coast has speeded-up following the Dam construction, due to loss of mud and silt deposition and loss of Lake-Sea currents This can result in transgression of the sea on these lakes, and calls for urgent measures for shore protection On the other hand, the benefits of the Dam to Egypt and Sudan in terms of agricultural expansion, hydro-electric power generated, industrialization and rehabilitation of populations are apparent

Benthic Substrates: Their Effect on Fresh‐Water Mollusca

Abstract: Mollusks have been collected in 650 locations in central New York State since 1966 in order to determine habitat preferences of the various species. Chemical and physical data were recorded at each locality. Three large lakes (Skaneateless, Otsego, and Oneida) were studies in detail to observe patterns of molluscan distribution. The species associated with different bottom types are tabulated. Mollusks are substrate distribution in typical environments are discussed. The lake studies show that definite relationships exist between mollusk distribution and substrate pattern. Species diversity is correlated with substrate diversity (r = 0.79) in 348 collection are that include several biotypes. See full-text article at JSTOR

Benthic Faunal Recovery in a Swedish Fjord Following the Closure of a Sulphite Pulp Mill

Abstract: During 1968-70, the recovery of the benthic macrofauna was investigated at 53 stations in Saltkallefjord, an inner branch of Gullmarsfjord on the west coast of Sweden. Physico-chemical analyses have shown that the water quality in Saltkallefjord improved as a result of reduced waste water discharge subsequent to discontinuance of production of sulphite pulp in 1966. After 1968, the benthic macrofauna has colonized fjord areas which earlier in the 1960's were azoic, or occupied by a poor fauna only. During May-October 1969, a successive monthly increase of the number of species appeared in these areas. Classification of some species in the succession is subject to discussion.

Differences in littoral fauna due to fluctuating water levels below a hydroelectric dam

Abstract: Water level fluctuations below a hydroelectric dam on the Connecticut River produce a freshwater "intertidal" zone. Along a transect in this zone from high to low water mark benthic invertebrates increased markedly in density and taxonomic diversity. Community composition shifted from chironomid–oligochaete predominance on the most exposed sites to mollusc predominance on the least exposed sites.

Species diversity of marine macrobenthos in the Virginia area

Abstract: Species diversity of benthic macro-organisms as measured by Shannon’s formula was highest on the outer continental shelf. Benthic diversity was higher in polyhaline zones of estuaries than on the shallow shelf and decreased sharply into the mesohaline zone, declining to the lowest in oligohaline zones. In addition to environmental stability and salinity regime, sediment grain size and pollution also affect species diversity. Analysis of the components of informational diversity, species richness and equitability indicates that the richness component accounts for most of the observed pattern, although both components are important to within-habitat differences.

A Preliminary Survey of the Benthic Macrofauna and Sediments in Lochs Etive and Creran, Sea-Lochs Along the West Coast of Scotland

Abstract: The hydrographic conditions in the two sea-lochs is briefly described where relevant to the survey of the benthos. Seasonal changes in temperature and salinity in Loch Etive appear to follow roughly the local coastal pattern but usually with a lag in timing that is considered to be because of the restricting effect of the twin sills. Replenishment of deep-basin water by ventilation over the sills is spasmodic and controlled by surface stratification; the latter being due primarily to freshwater runoff. This situation contrasts with Loch Creran which has only a small catchment and where the seasonal hydrography closely follows the pattern outside. Other possible reasons for the differences observed between the two lochs are discussed.The bottom fauna of both lochs was sampled semi-quantitatively with an anchor dredge at 22 stations in Loch Etive and 8 in Loch Creran at depths from 7–117 m. A detailed list of the fully marine fauna present is given. The species occurrences in the single-haul samples are compared objectively using a coefficient of similarity of the presence/absence records. An attempt is made to relate the groupings shown up to the classical ‘bottom community’ concept, to the feeding-type categories of the bottom animals and to analysis of particle size of sediment samples taken at the same stations. A correlation to sediment type was apparent. This is considered to owe as much to local hydrographic conditions which the sediment reflect as to the sediment itself.

The Benthic Fauna in Four Small Southern Appalachian Streams

Abstract: Monthly quantitative samples of benthic organisms were collected from streams in four different watersheds from August 1968 through July 1969. Each of the watersheds supports one of the following types of vegetation: old-field succession, hardwood forest, white pine forest with a few hardwoods, coppice forest. The kinds of organisms in the four streams were generally similar but their relative importance varied significantly. A Duncan's multiple-range test showed significant differences in the numbers of most taxa among the watersheds. The old-field stream had the greatest abundance while the coppice stream had the greatest standing crop biomass. The white pine stream had lowest standing crops of both numbers and biomass. Most of the differences among watersheds were attributed to different inputs of allochthonous detritus.

Palynological Evidence Bearing on the Ordovician-Silurian Paraconformity in Ohio

Abstract: Organic microfossils (spore tetrads, acrit-archs, scolecodonts, chitinozoans) from six Late Ordovician through Early Silurian samples (Elkhorn Formation of the Richmond Group; lower and upper beds of Belfast Member of the Brassfield Formation) straddling the Ordovician-Silurian paraconformity provide evidence about water depth. The spore tetrads appear to have been derived from plants growing in environments no deeper than an intertidal, semiterrestrial or very shallow-marine if not a nonmarine position. Their concentration on both sides of the paraconformity indicates at least shallower depth conditions than are present in the overlying upper part of the Brassfield Formation with its Eocoelia and succeeding deeper water Pentamerus benthic marine life zone faunas. A progressive deepening of water in the Early Silurian away from the paraconformity is also indicated by the inverse relationship existing between abundant spores in the basal bed of the Belfast Member and abundant Acanthomorphitae acritarchs in the upper bed. The presence of Sphaeromorphitae acritarchs in all sixsamples indicates that those microplankton are restricted to very shallow water depths. Spores from the Elkhorn Formation may have been derived from plants living in Ordovician time or they have “leaked” into the Elkhorn from the Silurian. In the former event, these spores may represent the oldest vascular plant remains recognized in North America.

Stratigraphic Record of Pollution in Shagawa Lake, Northeastern Minnesota

Abstract: Shagawa Lake in northeastern Minnesota is an anomalously productive lake in a region dominated by many very fresh and unproductive lakes. It receives treated sewage from the town of Ely. Mine wastes once entered the lake. A 1-m core of lake sediments was studied to ascertain the prehistoric trophic status of this lake and its response to mining, lumbering, and intensive human settlement in its watershed. Fossil diatoms, Cladocera, and some detrital minerals were identified and counted at 10-cm intervals throughout the core. A pollen stratigraphy of the upper 30 cm enabled the lacustrine changes to be related to vegetational changes during the last 100 yrs. The core contains three distinct zones. The lower zone (100 to 75 cm) is dominated by benthic and littoral diatoms and by a diverse assemblage of Cladocera. These features suggest that the littoral zone was more extensive or more productive or both than when the upper zones were deposited. The middle zone (75 to 25 cm) contains a planktonic diatom flora characterized by Cyclotella comta, a common form in the unpolluted lakes of this latitude. The upper zone (25 to 0 cm) contains abundant remains of Stephanodiscus minutus, Fragilaria crotonensis, and F. capucina, which are planktonic diatoms living today in the lake and in many highly enriched lakes to the south. This zone coincides with the appearance of hematite and limonite mineral grains that entered the lake when mining began in the area about 1890 and with an increase in ragweed (Ambrosia) pollen that marks land clearance and the beginning of European settlement. The cladoceran stratigraphy of the upper zone indicates that Chydorus sphaericus became much more abundant than Bosmina longirostris. This change was probably induced by the increasing severity and duration of blue-green algal blooms. The Stratigraphic changes that occurred at the time of European settlement indicate that Shagawa Lake responded rapidly to increased nutrient levels caused by a variety of human activities in and around the lake.

A Study of Nektonic and Benthic Faunas of the Shallow Gulf of Mexico Off the State of Mississippi As Related to Some Physical, Chemical, and Geological Factors

Abstract: A seasonal study of the nektonic and benthic faunas of the shallow Gulf of Mexico off Mississippi was conducted from January 1967 through May 1969. It was planned to sample monthly six fixed offshore stations at depths ranging from 5 to 50 fathoms in the open Gulf. In general this was carried out fairly well, as shown by Table 1, Water samples were taken from surface, midwater, and bottom levels each time a station was occupied, and temperatures and salinities were recorded for each of these. Samples were tested for the presence of nitrates, nitrites, ortho-phosphates and total phosphates. Secchi disc extinction points were recorded. Grab samples were taken for the determination of bottom composition. Plankton samples were taken from surface, midwater and bottom levels. Copepods, brachyuran zoea and megalops, stomatopod larvae, Lucifer faxonU Acetes a. carolinaCy Penilia avirostris^ Voliolum sp. and fish eggs and larvae were present in greatest abundance. Surface and benthic nekton samples were obtained. Dredge samples were made quarterly and twelve invertebrate species and three species of fishes were collected. Renilla miilleri was the most abundant species taken, and the fish catch consisted of Centropristes ocyurus, Citharichthys spilopterus and Etropus crosaotus. Accounts of 50 invertebrate species (24,679 specimens) and 129 fishes (93,563 specimens) taken in trawl hauls is presented. Temperature and salinity data are given for all species. Relative abundance, seasonal bathymetric distributions and movements, apparent growth patterns, catch per unit of effort and various biological data are noted for the most abundant species. Station 5 (40 fathoms) produced the largest percentage of trawl catches {22.1). Jtenilla miilleri was the most abundant invertebrate taken in trawling. The brown shrimp, Penaeus aztecus, was second in abundance (10.92%). The five most abundant species comprising 80.57% numerically of the catch were croaker, longspine porgy, butterfish, spot, and seatrout. The species comprising 91.89% of the catch by weight were the croaker, longspine porgy, spot, seatrout, lizardfish, butterfish, pinfish, bank sea bass, sea catfish and black fin sea robin. The families Sciaenidae, Sparidae and Stromateidae were represented by the greatest numbers and comprised 82.9% of the total catch. Families considered to be of commercial importance contributed 92.9% to the total fish catch. 2 GULF RESEARCH REPORTS

The flux of particulate carbon in an estuary

Abstract: The major sources and sinks of suspended particulate carbon are identified for northern Chesapeake Bay, Maryland, USA. The area of the bay under consideration was divided into two sections. The northernmost section (upper bay), from the head of the bay to the vicinity of Baltimore, was characterized by a high input of particulate carbon from upland drainage. The section from Baltimore to the mouth of the Potomac River (middle bay) was dominated by an internal supply of particulate carbon from primary production. The northernmost section was characterized by major particulate carbon losses to the bottom and to benthic respiration, with slightly less than half (43%) of the particulate carbon respired in the water column or converted to dissolved organic matter. In contrast, respiration in the water column or conversion to dissolved organic matter was responsible for the loss of about 65% of the particulate carbon in the middle section of the bay, while losses to the bottom and to benthic respiration totaled only 12%. Even though the supply of particulate carbon to the upper bay was about 1.5 times the supply to the middle bay, the loss of carbon due to biological activity (biological efficiency) in each area was similar, and amounted to about 70% of the supply of particulate carbon.

On the Chemical Composition, Distribution and Ecology of Some Common Benthic Marine Algae from Iceland

Abstract: Introduction The original Intention of these algologkal investigations around the Icelandic coast was to make an äs complete äs possible review of the littoral algal flora, which had not been mvestigated in detail since HELGI JONSSONS work (1901; 1903; 1910; 1912). According to old Icelandic literature (e. g. BISKUPA SÖGUR, 1958; EGILS SAGA, 1892; GRAGÄS, 1852; HALLDORSSON, 1783; MOHR, 1786; HORNEMANN» 1806; Hj ALTALIN, 1854, 1868, 1878; STEPHENSEN, 1808; STURLUNGA SAGA, 1908; THORBJARNASSON, 1939 and others) different species of seaweeds have been used in Iceland for more than a thousand years. Due to industrial development in the last decades, different species of marine benthic algae have come more and more into the sphere of interest äs basic raw material for different branches of industry, The Icelandic coast, however, represents a rieh source of algal raw rnaterial, until now not fully explored or investigated from this point of view, although some attempts were made to produce Ascophyllum meal in the years 1939—1941 and again in 1960 (HALLSSON, 1964). L·ammaria species were burnt for kelp between 1903 and 1908, and further some species were used äs manure, fuel, for miscellaneous medical purposes and for human consumption. The present work is primarily focused on the floristic cornposition and ecology of the benthic algal Vegetation around the Icelandic coast. These investigations were carried out with the help of grants from the Icelandic Research Foundation (Visindasjoöur) and were started in 1963 and are still going on. Eight summers have been spent in collecting algal material around the Icelandic coast. During these investigations special attention has been paid to the changing features of the Vegetation pattern around Iceland, due to the influence of difFerent hydrographic conditions, thus the influences of Arcticand Atlantic waters. The southern coast is strongly influenced by the Gulf stream. This Atlantic influence diminishes towards the north. The Irminger Current, conveying Atlantic water along the north coast gets cooled and diluted during its passage over the insular shelf (STEFÄNSSON, 1962). Here, the nearness of drif t ice äs well äs the influx of waters of the Hast Greenland Current and the nearness of the East Icelandic Current greatly influences the l i t tora l al^al growth. The mid-eastern coastal area is however inf luenced by the East Icelandic Current, conveving water of V r c r i c origin. The areas of delirnitation between the Arctic and Atlantic waters are subjected to seasonal and annu i t l translocations and are found, according to S tc f i ins^on (1962) on the line between Eystrahorn and Vestrahorn in the SE and north of Gerpir in the mid-east. Local variations of the algal flora, induced by temperaturc and salinity, were likewise in the sphere of interest. As a fragrnent of this work, the chemical compos density, distribution and ecology of some of the common and abundant species, encountered around rhc coast of Iceland is treated here. Some of these species could possibly be used äs raw material for different purposes in the future, and these preliminary data would provide a basis for the evaluation and furcher study of these species, During the last years, the Laminaria species from the Icelandic coast have come into the sphere of interest äs raw material for alginic acid. Ifs in the future, the harvesting and preparation o£ these quantitatively dominant species was to become a reality, it would only require a modification of the technological process for some other specieSj occurring in considerable amounts, to be harvested and dried äs well, though for different purposes. As mentioned, the present author's investigations are mainly focused on the algal Vegetation of the littoral slopeSj tide-pools and shallows3 the investigations of the deeper regions will have to be done by others, Fucacean species covering extensive surfaces in the littoral in some areas of the Icelandic coast, could possibly be harvested in the near future. With this in mind> the density and chemical composition of Ascophyllum nodo$um> on the extensive littoral slopes around Eyrarbakki ans Stokkseyri (Southern Iceland) was studied by the same author in 1963 (MUNDA, 1964). Apart from the Fucaceae and Laminariaceae, only the most common and abundant components of the Icelandic algal flora are treated here, thus species, which proved to be essential components of the Vegetation pattern in difFerent areas.

The effect of industrial effluent from pulp and paper mills on the marine benthic environment

Abstract: The types of effluent discharged by wood-processing industries and their effects on the benthic environment are described. A brief summary of the results of the Lochs Linnhe-Eil survey 1964-70 is given. Populations of the molluscs Corbula , Thyasira and Myrtea have increased in most areas, and appear to be favoured by a moderate increase in the organic input to the system. Corbula dominates in the shallower polyhaline areas, and Myrtea in the deeper mixoeuhaline areas. On sediments with a high natural leaf litter content a low diversity fauna occurs, dominated by the annelids Cirriformia , Peloscolex , Capitella and Staurocephalus , and the crustacean Idotea . The predominance of this kind of fauna has increased in its area of occurrence in recent years. Comparisons of these faunal distributions and changes with those found in surveys in other marine areas affected by wood-processing wastes and other types of organic effluents show considerable similarities in the faunal changes occurring under increased organic loading. The utility of ‘indicator’ species in the assessment of organic pollution is briefly discussed. The need for detailed information on the ecological and physiological reasons underlying the varied faunal successions which occur under conditions of pollutional stress is emphasized.

The benthic macrofauna of moriches bay, new york

Abstract: Quantitative sampling of the subtidal macro-benthos of a shallow temperate lagoon shows several structural features of benthic communities in five biotopes. Attempts are made to relate past and present qualities of benthic structure to long-term nutrient and organic loading of this lagoon. While overall benthic species composition has apparently not changed drastically since a 1938 qualitative survey, some important changes in dominant species composition appear to be associated with the biology of these principal species. The best estimate of average annual standing crop of the macro-benthos (< 5 g/m2, ash-free dry weight) is lower than estimates in somewhat comparable estuaries, apparently because of low oxygen concentrations over extensive areas during summers, which derive in turn from large summer influxes of nutrients and organic matter into this poorly flushed lagoon. Clear-cut associations between sediment type and mode of feeding of the benthos are demonstrated; suspension feeding invertebrates d...

Observations on the role of dissolved organic compounds in the nutrition of benthic invertebrates: II. Uptake by other animals living in the same habitat as pogonophores, and by some littoral polychaeta

Abstract: New observations on uptake of 14G labelled amino acids, glucose, and fatty acids by polychaetes and an echinoderm from the same habitats as pogonophores are compared with results already published for uptake by the pogonophores. Comparison is also made with new and published data on uptake by estuarine polychaetes. There is no great difference between the pogonophores ar_d the other animals in the maximum rate of uptake found per unit weight per hour, but the pogonophores seem better adapted to take up from lower external concentrations.

Analyses of Benthic Community Structure in a Reservoir by Use of Diversity Indices

Abstract: Benthic macroinvertebrate and physicochemical collections were made monthly in four bays of Keystone Reservoir, Oklahoma, from early November 1965 through October 1966. Benthic community structures were subjected to species diversity analyses and the results were related to selected physicochemical estimates. A total of 25 benthic macroinvertebrate species were collected. There was a high, inverse correlation between diversity (d) and conductivity, and between d and depth. There was a direct, high correlation between conductivity and depth. There were significant differences in annual diversity (d) between bays which differed in water quality. Diversity indices were an easy and reliable method of determining long-term effects of waters of different qualities on the benthic fauna within reservoirs. The method should be of equal value when used on an entire reservoir, or in making comparisons between reservoirs.

Collections and Submarine Observations of Deep Benthic Fishes and Decapod Crustacea in Hawaii

Abstract: Depths between 150 and 400 m off Oahu, Hawaii, were surveyed by submarine, gill nets, and traps. Depth of capture or observations and other data are given for 47 species of fishes and 20 species of decapod Crustacea. Of these species, 10 fishes and five crustaceans are either undescribed or new records for Hawaii. Four other fishes collected and several others observed from the submarine are probably undescribed or unrecorded species. A large proportion of both the total number of species collected and of the new forms were taken by gill net. The gill nets are able to sample steep, rocky bottoms and obtain types of organisms inaccessible to other types of gear, particularly bottom trawls. THE DEEP WATER BENTHIC FAUNA of the Hawaiian Islands is known mainly from results of deep bottom trawling by the Albatross near the turn of the century (Gilbert, 1905) and from a few subsequent trawling-dredging collections. Such collections have undoubtedly missed some forms and, as Gosline (1965) has noted, data on depth distribution are inadequate. Brock and Chamberlain (1968) and Strasburg, Jones, and Iverson (1969) have reported on submersible observations down to about 200 m. These data have extended depth ranges and provided interesting observations on many organisms, but, because of the depth limits of the submersible, have included few deep-water species. The only other sources of deep-water specimens have been fishermen who have collected occasional individuals by handline, and volcanic eruptions during which specimens have floated to the surface following lava flows into deep water (Gosline, Moore, and Yamaguchi, 1954). This paper presents results of a survey during which a submersible and several types of fishing gear were utilized. The efforts were concen1 Hawaii Institute of Marine Biology Contribution no. 368. This work was supported by State of Hawaii Fisheries Funds to the University of Hawaii and by Sea Grant GH-62 and GH-93. Manuscript received 6 December 1971. 2 University of Hawaii: Department of Oceanography Honolulu, Hawii 96822, and Hawaii Institute of Marine Biology, P. O. Box 1067, Kaneohe, Oahu, Hawaii. trated on steep, rocky bottoms between 150 and 400 m depths. The investigation was restricted to fishes and decapod Crustacea. The results provide records of several species new to Hawaii, depth ranges of these and many others, information on the habits of some species, and a basis for comparing the effectiveness of different survey methods.

Benthos Trapped Leaving the Bottom in Bideford River, Prince Edward Island

Abstract: Inverted funnel traps, designed to catch animals swimming up from the bottom, set in Bideford River estuary, P.E.I., during the summer of 1969 caught numerous benthic and hyperbenthic invertebrates...

The Benthic Marine Algae of Delaware, U.S.A.

Abstract: Field studies carried out between 1962 and 1968 along the Atlantic coast of Delaware, USA, and the southern shores of Delaware Bay, revealed the presence of 74 different taxa of marine algae, 69 of which are benthic Of these benthic taxa 11 belong to the Cyanophycophyta, 21 to the Chlorophycophyta, 1 to the Xanthophycophyta, 18 to the Phaeophycophyta, and 18 to the Rhodophycophyta As reported in my Preliminary Checklists (Zaneveld, 1966a, 1967), almost all benthic taxa are new records for the State of Delaware, eg 11 belonging to the Cyanophycophyta, 18 to the Chlorophycophyta, 1 to the Xanthophycophyta, 16 to the Phaeophycophyta and 11 to the Rhodophycophyta The reproductive periodicities of the taxa are tabulated, showing that the maximum reproductive periods for most taxa extend from early May to late September